The existence of Factor VII was first recognized in serum* ( 1). A one-stage method for the quantitative determination of this factor has been proposed ( 1 ) ; it yields practically the same results with plasma or serum.+ Separation of Factor VII from prothrombin offers considerable difficulties, although the physiological behavior of these two clotting factors are entirely different: Factor VII accelerates conversion of prothrombin to thrombin; prothrombin. on the other hand, determines quantity of thrombin formed. The two factors can be partly separated: a) by the clotting process itself, more than 95% of prothrombin being consumed: whereas Factor VII remains unchanged in the serum; b) by dicumarol and similar anticoagulants which cause a more rapid decrease of Factor VII-concentration at the beginning of therapy. The difficulty of the chemical separation of Factor VII and prothrombin is a consequence of the similarity of their physico-chemical properties. No separation can be obtained by fractional precipitation with different salts, organic solvents, or their combined use. Fractional adsorption on barium sulfate, tricalcium phosphate, etc., also is ineffective. The relative amounts of the two factors remain unchanged after such procedures. Only by means of chromatography is it possible to isolate prothrombin and Factor VII. Prothrombin and Factor VII are separated from fibrinogen and Factor V by adsorption on barium sulfate, the mixture pro-~ ~~ ~~~ * Factor \;I1 is almost certainly identical with SPC.4 oi Alexander et aZ.(2), co-thromboplastin of Mann and Hurn(3), proconvertin of Owren(4), stable prothrombin conversion factor of Owen and Bollmann(5), and the accelerator factor of Mac-Millan (6) . t In undiluted plasma and serum, results obtained by the one-stage method are somewhat different; this is due to a difference i n the prothrombin content of plasma and serum. After dilution (1:lO) results of Factor \'I1 assay are identical in plasma and serum. University of Zurich, Switzerland.thrombin-Factor VII is then chromatographed. By this chromatographic procedure, first pure prothrombin and later pure Factor V I I are obtained.Method. Purification of Factor V I I from plasma. The first two steps are carried out at 2"C, the third and fourth at room temperature.Step I . Adsorption. 10 g of barium sulfate (Merck feinst gepulvert, Germany) are suspended in 2 0 0 cc of oxalated plasma. The suspension is stirred for 40 min., then centrifuged. The supernatant, containing fibrinogen and Factor V, is discarded.Step 2. Washing. The barium sulfate is washed twice with 30 cc of physiological saline. The solution is discarded.Step 3. Preparation of column for chromatography. A homogenous mixture of barium sulfate (10 g) and hyflosupercel ( 5 g) suspended in physiological saline is introduced into the column. The excess of saline is again discarded.Step 4. Elution. The prothrombin is eluted by means of 150 cc of .14 molar trisodium citrate-citric acid solution at pH 5.8. The elution is continued with a .14 molar trisodium...
Background In chronic immune thrombocytopenic purpura (ITP), rituximab removes the harmful autoantibodies through antibody-dependent cellular cytotoxicity. The response to rituximab in ITP is variable; the effectiveness of rituximab is influenced by the process of activation of effector fragment C gamma receptors (FcγRs). Genetic factors may affect the response to rituximab. Objectives The influence of FcγRIIa (H131R) and FcγRIIIa (V158F) gene polymorphisms on the response to rituximab in ITP. Methods One hundred ITP patients were genotyped for FcγRIIa (H131R) and FcγRIIIa (V158F) gene polymorphisms using the polymerase chain reaction-restriction fragment length polymorphism assay. The response at the end of the third month was assessed by direct platelets count. Polymorphisms were analyzed in relation to the response. Results The mean platelets count at end of weeks 1-4 of rituximab was statistically significantly higher in patients who achieved complete response (CR) than partial response or no response (P-value = .001). Although RR (44.4%) and HR (38.9%) genotypes were observed to be higher in patients who achieved CR compared with the wild (HH) genotype (16.7%), it was not statistically significantly different (P-value = .648). Conclusion The higher platelet count achieved early is predictive for a better response to rituximab later. FCγRIIA polymorphisms did not significantly influence response to rituximab in ITP.
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